They were hunted down by FC troops, who killed three of them and apprehended a fourth, he added.

The FC spokesman did not say anything about identity of the attackers.

"A group of attackers riding motorbikes intercepted the oil tankers near Dhadar area (Bolan district), forced the crew to get off and set the tankers on fire before speeding away," Dolan Deputy Commissioner Waheed Shah told Anadolu Agency.

Attackers shot and injured a driver who offered resistance, he added.

The tankers were transporting oil for NATO troops in neighboring Afghanistan.

They were attacked in Bolan, some 120kms east of Quetta, the capital of the mineral-rich Baluchistan province.

Shah said the tankers were on their way to Chaman border, one of the two key supply routes to war-stricken Afghanistan.

No group has claimed responsibility for the attack until the filing of this report.